Just to make me understand the business plan better: why would people or companies to be willing to pay much more to have their data (or computations) done in space?

The only reason that I can imagine is that the satellite which contains the data center also has a lot of sensors mounted (think military spying devices), and either for security, capacity or latency reasons you prefer the sensor data to be processed in space instead of transferring it down to earth, process it there, and sending the results back to space.

In other words: the business model is getting big money defense contracts (somewhat ignoring whether the idea really makes military sense or not).